http://www.gnu.org/licenses/gpl-2.0.html
https://www.gnu.org/licenses/old-licenses/gpl … 2.0-faq.en.html

I would like to bundle GPLed software with some sort of installation software. Does that installer need to have a GPL-compatible license?
>> No. The installer and the files it installs are separate works.

I downloaded just the [GPLed] binary from the net. If I distribute copies, do I have to get the source and distribute that too?
>> Yes. The general rule is, if you distribute binaries, you must distribute the complete corresponding source code too.

Dosbox + some DOS program, is it "mere aggregation" or "combining two modules into one program"?
IANAL, but I would say it falls under:
"The interpreted program, to the interpreter, is just data; the GPL doesn't restrict what tools you process the program with."

aqrit, thanks a lot, you cleared some points!

First, I'd like to congratulate you for selecting Vogons for your legal council. 😵

Providing source could be as simple as putting up a Github/Gitlab/SF repository with the source onboard (if you distribute via the internet). It doesn't have to be provided "in the box", it just has to be accessible to users. You're also obligated to fulfill any further requests for source if online methods are not practical for a downstream user, although you can recover your postage and medium expenses for this.

In general, for such matters:
1) Take advantage of the published resources re: GPL/LGPL/AGPL compatibility.
https://www.gnu.org/licenses/gpl-faq.en.html
https://www.softwarefreedom.org/resources/200 … ance-guide.html

2) If the published resources don't clarify your questions completely, contact the SFLC for a more in depth explanation.
https://www.softwarefreedom.org/about/contact/

3) If your interest doesn't fully align with GNU or the SFLC, consider retaining council for an independent legal opinion.